Self-cleaning valve plug and seat assembly

Abstract

A self-cleaning valve plug and seat assembly for use within a valve chamber comprises a seat member extending into the chamber and having an inwardly converging frustconical seating surface thereon. A cylindrical skirt portion extending inwardly coaxially from the seating surface includes ports therein connecting with a fluid passage extending axially through the seat member. A valve plug includes a cylindrical bore extending partway thereinto and adapting the plug for sliding movement over the seat member skirt portion. The plug includes a surface intersecting the bore at an actute angle to provide a circular cutting edge at the open end of the bore. Means are provided for moving the plug axially toward and away from the seat member so that the plug is disposed clear of the seat member ports in the open valve position and covers the ports in the closed valve position with the plug cutting edge engaging the seating surface of the seat member in fluid-tight sealing relation.

I claim: 
     
       1. A self-cleaning valve plug and seat assembly comprising a seat member and a valve plug, said seat member comprising a cylindrical skirt portion and a substantially frusto-conical seating surface coaxial with said skirt portion and converging toward and intersecting said skirt portion at an obtuse angle, a fluid passage extending through said seat member, and at least one port in said skirt portion connecting with said fluid passage; said valve plug comprising a cylindrical bore extending partway thereinto to permit sliding telescoping movement of said valve plug along the exterior of said seat member skirt portion, said plug having a circular cutting edge adjacent the open end of said bore, said cutting edge being formed by a surface of revolution and having an axis concentric with the axis of said plug bore and converging toward and intersecting said plug bore at an acute angle, and means for moving said plug toward and away from said seat member seating surface, said plug uncovering said valve member port in the open position of said assembly, said plug covering said port and said cutting edge engaging said seating surface in fluid-tight sealing relation in the closed position of said assembly. 
     
     
       2. The invention as claimed in claim 1 wherein said cutting edge is formed by the intersection of a frusto-conical surface of said plug with said plug bore. 
     
     
       3. In a valve comprising a hollow valve body defining a closed valve chamber therewithin, an inlet port in said body for connecting said chamber to a fluid source, an outlet port in said body for draining fluid from said chamber, a valve seat member having a fluid passage therein communicating with said outlet port, a valve plug within said chamber cooperatively mounted for selective movement with respect to said seat member to open and close said fluid passage therethrough, and means for selectively moving said plug with respect to said seat element, the improvement wherein said seat member comprises an inwardly extending cylindrical skirt portion and an inwardly converging seating surface, said inwardly extending cylindrical skirt portion of said seat member coaxial with and intersecting said seating surface, said seating surface comprising a surface of revolution converging toward and intersecting said skirt portion forming an obtuse angle with said skirt portion at its intersection therewith, the fluid passage of said seat member extending generally axially through said seat member, and at least one port in said skirt portion connecting said fluid passage with said valve chamber; said valve plug comprising a cylindrical bore extending partway thereinto and adapting said plug for sliding telescoping movement over said seat member skirt portion, said plug having a circular cutting edge formed by a surface of revolution and having an axis concentric with the axis of said plug bore and converging toward and intersecting said plug bore at an acute angle, said plug being clear of said skirt portion port in the open position of said valve, said plug covering said port and said cutting edge engaging said seating surface in fluid-tight sealing relation in the closed position of said valve. 
     
     
       4. The invention as claimed in claim 3 wherein said cutting edge is formed by the intersection of a frusto-conical surface of said plug with said plug bore. 
     
     
       5. The invention as claimed in claim 3 wherein said seating surface comprises a frusto-conical surface. 
     
     
       6. In a valve comprising a hollow valve body defining a closed valve chamber therewithin, an inlet port in the upper end of said body for connecting said chamber to a fluid source, an outlet port in the lower end of said body for draining fluid from said chamber, a valve seat member having a fluid passage therein communicating with said outlet port, a valve plug within said chamber cooperatively mounted for selective movement with respect to said seat member to open and close said fluid passage therethrough, and means for selectively moving said plug with respect to said seat element, the improvement wherein said seat member comprises an upstanding and inwardly extending member with the fluid passage thereof aligned substantially vertically, said seat member comprising a frusto-conical seating surface spaced above the lower end of said chamber, an inwardly extending cylindrical skirt portion of said seat member coaxial with said seating surface, said seating surface converging toward and intersecting said skirt portion at an obtuse angle, at least one port in said skirt portion connecting said fluid passage with said valve chamber; said valve plug comprising a cylindrical bore extending partway thereinto and adapting said plug for sliding telescoping movement over said seat member skirt portion, said plug having a circular cutting edge adjacent the open end of said bore, said cutting edge being formed by a frusto-conical surface of said plug and having an axis concentric with the axis of the plug bore and converging toward and intersecting said plug bore at an acute angle, said plug being clear of said skirt portion port in the open position of said valve, said plug covering said port and said cutting edge engaging said seating surface in fluid-tight sealing relation in the closed position of said valve. 
     
     
       7. The invention as claimed in claim 6 wherein said valve plug includes an upper outwardly and downwardly sloping surface adapted to direct particulate matter away from said port. 
     
     
       8. The invention as claimed in claim 6 wherein said means for selectively moving said plug with respect to said seat element comprises a temperature sensitive means for automatically actuating said plug in response to temperature changes of the fluid within said valve chamber. 
     
     
       9. The invention as claimed in claim 6 including a plurality of ports in said skirt portion connecting said valve chamber with said fluid passage in the open position of said valve.